The National MS Society frequently fields questions about functional electrical stimulation (FES) — usually in relation to the products WalkAide from Innovative Neurotronics, NESS L300™ from Bioness® and the Odstock Dropped Foot Stimulator from Odstock Medical Limited in the United Kingdom.
Following is some information about what scientists know — and what they still need to learn — about the effectiveness of these devices for people with MS.
Overview of FES devices
Most MS rehabilitation specialists recommend physical therapy and, if needed, a brace or “ankle foot orthosis” to treat foot drop. The brace, which is usually made of plastic, is worn around the lower leg and foot. It supports the ankle and holds both foot and ankle in a flexed position.
Two new devices — the WalkAide and NESS L300 — are now on the U.S. market to alleviate foot drop. They work by sending low-level electrical impulses to the peroneal (sometimes called fibular) nerve, which signals leg muscles to lift the foot. Seen as easier to wear and more convenient by many users, they are also a great deal more expensive — about $5,000-$6,000 — and typically not covered by insurance.
The FES products used for foot drop are reputable, but not everyone with MS experiences positive results. For the devices to work, the peroneal nerve must be capable of sending a signal and the muscles must be capable of receiving it. In MS, a variety of complications may prevent this from happening.
Since scientific studies on FES and foot drop have focused primarily on people who have had a stroke, we do not have enough data yet to know how broadly useful such products might be for people with MS as a whole.
Prospective users need to check out the terms associated with product trials. The Society has received reports of patients losing their deposits when they wanted to return the devices after finding them ineffective.
National MS Society Resources on Walking and FES
Frequently Asked Questions About FES Devices
What Is Functional Electrical Stimulation?
Functional electrical stimulation (FES) is a technique that uses low levels of electrical current to stimulate nerves, innervating extremities affected by impairment resulting from spinal cord injury (SCI), head injury, stroke or other neurological disorders.
FES is not a cure but may restore or improve function in nerves that control specific muscles or muscle groups. FES can have therapeutic effects in some cases but it does not repair or regenerate the damaged spinal cord. FES is also referred to as Functional Neuromuscular Stimulation (FNS) or Neuromuscular Electrical Stimulation (NMES).
Some people with multiple sclerosis have found FES helpful in alleviating foot drop. Foot drop is a condition caused by weakness or paralysis of the muscles involved in lifting the front part of the foot. It makes walking a challenge, causing a person to either drag the foot and toes or engage in a high-stepping walk called steppage gait. The nerve runs along the outside of the lower leg below the knee.
Other applications for FES include standing, bowel and bladder control, male sexual and reproductive assistance, and breath control. Medical benefits of FES may include prevention of muscle disuse or weakness, increase of local blood flow, muscle strengthening, maintained or increased joint range of motion, reduced incidence of urinary and bladder infections, osteoporosis prevention and cardiovascular health. Improved functionality and greater independence may lead to psychological benefits.
How Does FES Stimulation Work?
A small, self-contained device attaches to the leg below the knee, counteracting foot drop by electronically stimulating the peroneal (sometimes called fibular) nerve, thus allowing foot lifting. During the swing phase of walking, the device electrically stimulates the appropriate muscles that cause ankle dorsiflexion and may thus improve the person’s walking ability.
Will Insurers Cover FES Devices?
Private insurance typically will not pay for an FES device. The companies marketing WalkAide and NESS L300 report that they are working on securing Medicare coverage, but couldn’t provide a timeline.
How Can a Person With MS Tell if an FES Device Might Help?
Although there are no studies specifically supporting the use of FES for foot drop in MS, National MS Society medical advisers say they can be helpful for some people.
People who are considering FES should first consult with their physician to determine if they have the kinds of symptoms that may be helped by FES. If their symptoms are appropriate for FES, they should ask for a referral to a physical therapist who can work with them to evaluate whether FES is effective for them before making the purchase. The Society recommends not purchasing an expensive product without first having an opportunity to test whether it will be beneficial.
Some Medical Literature about FES
1. NeuroRehabilitation. 2007;22(4):335-7.
FES cycling reduces spastic muscle tone in a patient with multiple sclerosis. Krause P, Szecsi J, Straube A.
Department of Neurology, University of Munich, Germany.
We report on a multiple sclerosis patient who received functional electrical stimulation to reduce spastic muscle tone of the lower limbs. Stimulation by means of surface electrodes applied to the thigh muscles induced cycling leg movements. Spastic muscle tone was measured clinically using the modified Ashworth scale and semiautomatically by pendulum testing of spasticity. This was done before and directly after stimulation. The patient was able to endure the stimulation for ca. 30 minutes; there was a significant reduction of spasticity after each stimulation session.
We conclude that this type of stimulation could be another potential treatment modality for multiple sclerosis patients, especially those with a high score in the expanded disability Status scale.
PMID: 17971625 [PubMed - indexed for MEDLINE]
2: Arch Phys Med Rehabil. 1999 Dec;80(12):1577-83.
Clinical use of the Odstock dropped foot stimulator: its effect on the speed and effort of walking.
Taylor PN, Burridge JH, Dunkerley AL, Wood DE, Norton JA, Singleton C, Swain ID.
Department of Medical Physics and Biomedical Engineering, Salisbury District Hospital, Wiltshire, United Kingdom.
OBJECTIVE: To assess the clinical effectiveness of the Odstock dropped foot stimulator by analysis of its effect on physiological cost index (PCI) and speed of walking. This functional electrical stimulation (FES) device stimulates the common peroneal nerve during the swing phase of gait. DESIGN: A retrospective study of patients who had used the device for 4 1/2 months. SUBJECTS: One hundred fifty-one patients with a dropped foot resulting from an upper motor neuron lesion. SETTING: A medical physics and biomedical engineering department of a district general hospital specializing in the clinical application of FES and a neurophysiotherapy department at a separate hospital.
MAIN OUTCOME MEASURES: Changes in walking speed and effort of walking, as measured by PCI over a 10-meter course. RESULTS: There was a 92.7% compliance with treatment. Stroke patients showed a mean increase in walking speed of 27% (p<.01) and reduction in PCI of 31% (p<.01) with stimulation, and changes of 14% (p<.01) and 19% (p<.01), respectively, while not using the stimulator. Multiple sclerosis patients gained similar orthotic benefit but no "carry-over." CONCLUSIONS: The measured differences in walking with and without stimulation were statistically significant in the stroke and multiple sclerosis groups. In this study use of the stimulator improved walking. Those with stroke demonstrated a short-term "carry-over" effect.
PMID: 10597809 [PubMed - indexed for MEDLINE]
3: Mult Scler. 2010 Sep;16(9):1141-7. Epub 2010 Jul 2.
Impact on activities of daily living using a functional electrical stimulation device to improve dropped foot in people with multiple sclerosis, measured by the Canadian Occupational Performance Measure.
Esnouf JE, Taylor PN, Mann GE, Barrett CL.
The National Clinical FES Centre, Salisbury District Hospital, Salisbury, Wiltshire, UK.
OBJECTIVE: To determine if the Odstock dropped foot stimulator (ODFS), improved Activities of Daily Living for people with multiple sclerosis.
METHOD: 64 people with unilateral dropped foot due to secondary progressive multiple sclerosis took part in a randomized controlled trial. Research volunteers were assigned to a group using the ODFS or a group who received physiotherapy exercises for 18 weeks. Outcome measures were the Canadian Occupational Performance Measure (COPM) and a falls diary.
RESULTS: Results of 53 research volunteers are reported. Improvements in performance and satisfaction scores were greater in the ODFS group than the exercise group; (p < 0.05). Use of the ODFS was also perceived as effective in reducing tripping and increasing walking distance. The median number of falls were 5 in the ODFS group and 18 in the exercise group (p = 0.036) over the study period.
CONCLUSION: The study shows that people with multiple sclerosis using the ODFS increased their COPM performance and satisfaction scores of their identified problems of Activities of Daily Living more than a matched group who received physiotherapy exercises. ODFS users also experienced fewer falls. Read more about this study.
PMID: 20601398 [PubMed - in process]